We provide a brief review of Boolean logic, the circuit model of computation, and I show how to assemble logic gates from their Boolean components. I present examples of classical circuits, including the half, full and ripple adder, and discuss reversible and irreversible gates. Quantum logic gates, including the Pauli, Hadamard and controlled-not gates are introduced, and we learn how to construct quantum circuits from them. The notions of quantum parallelism and interference enable Deutsch’s algorithm, the first proof-of-principle for quantum advantage. We dissect the quantum circuit for the Deutsch-Josza algorithm and demonstrate its ability to perform massively parallel computations; a capability inaccessible to machines based on the bit paradigm. We introduce and discuss the unitary time development of quantum states.